This invention relates to battery chargers and, in particular, to battery chargers having control circuits including reverse polarity protection and high-rate charging control.
It is known to provide a battery charger in which full-wave rectified current is supplied to a battery through a silicon controlled rectifier. By controlling the timing of the gating pulse applied to the SCR the average charging current is controlled. An oscillator circuit formed by a unijunction transistor with a timing capacitor in its emitter circuit provides the necessary gating pulses. The charging rate of the capacitor is controlled to alter the period during which the SCR is conductive. This control of capacitor charging rate is provided by a circuit responsive to battery voltage and by a circuit responsive to charging current.